Dynamoelectric apparatus



Oct. 3, 1950 wlNTHER DYNAMOELECTRIC APPARATUS Filed May 6, 1949 FIGZ.

i 'atented Oct. 3, 1950 DYNAMOELECTRIC APPARATUS Anthony Winther, Kenosha, Wis., assignor to Martin P. Winther, Waukegan, 111., as trustee Application May 6, 1949, Serial No. 91,791

This invention relates to dynamoelectric apparatus, and, more particularly, to eddy-current apparatus adapted for use as clutches, brakes, dynamometers and the like.

Briefly, this invention involves a novel arrangement of low electrical resistance end rings in the magnetic inductor drum of eddy-current apparatus having a field member comprising clawtype poles, for use as a clutch, brake, dynamometer or the like, for the purpose of reliably obtaining higher torque capacity with apparatus of a given size. I have found that the position of low resistance end rings, relative to the ends of the pole faces of the claw-type poles, is of utmost importance as regards the torque capacity of such apparatus. If the inside edges of the end rings are axially spaced a distance less than the axial extent of the pole faces and the pole faces project slightly beyond the inside edges of the rings, the torque capacity of the apparatus is increased over and above what it would otherwise be. Accordingly, the invention briefly involves dynamoelectric apparatus of the type having a magnetic inductor drum provided with low electrical resistance end rings and a field member having claw-type poles wherein the poles faces project slightly beyond the inside edges of the end rings to provide apparatus of increased torque capacity for its size. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a longitudinal section through apparatus embodying the invention;

Fig. 2 is a fragmentary section taken substantially on line 22 of Fig. 1;

Fig. 3 is a section taken substantially on line 33 of Fig. 2 and showing a, bottom plan View of one pole;

Fig. 4 is an enlarged ring section showing in side elevation a single claw-type pole and showing certain surface line elements; and,

Fig. 5 is a developed section taken substantially on line 5-5 of Fig. 1, just within certain pole faces illustrating several of the latter and showing how certain end rings are related thereto.

Similar reference characters indicate corre- 4 Claims. (01. 172-284) respectively,

sponding parts throughout the several views of the drawings.

Referring more particularly to Fig. 1, there is or driven member (if it is a slip coupling) and either the rotating or stator member (if it is a brake, dynamometer, motor or generator). It has a substantially uninterrupted outer cylindric surface. At numeral 3 is shown an annular field coil in a cylindric homogeneous magnetic iron ring member 5. Fastened to the member 5 on opposite sides of the coil 3 arehomogeneous magnetic iron rings 1 and 9, which are, formed with annular series of spaced magnetic claw-type teeth or poles H and IS. The respective teeth I l and I3 are staggered, interdigitated, point in opposite directions, and envelop the coil 3. The claw-type teeth or poles are rooted in the rings, and their non-root portions form extensions. As illustrated herein, they are of the form particularly shown in the copending application of myself and Martin P. Winther entitled Toroidal Magnet Fields for Dynamoelectric Machines, Serial No. 25,246, filed Mayv 5, 1948, eventuated as U. S. Patent No. 2,470,596, dated May 17, 1949. The invention, however, is not to be construed to be limited to the exact form of pole as shown in said copending application. Also, while the magnetizing element is shown herein as a coil 3, it is to be understood that other annular magnetizing elements may be used, such as for example, an annular permanent magnet.

The rings I and 9 are attached to the ring 5 as by welding or otherwise. The parts 3, 5, 1, 9, H and I3 all rotate as a unit assembly and may form the driving or driven field member if the device is a slip coupling; and either the rotating or stationary field member if the device is a brake or dynamometer; or it may be the field of a motor or generator. Details of the rotary or other mountings for either of the relatively r0- tary assemblies thus far described are not included herein, since such are known.

The rings 1 and 9 carry their respective pole teeth H and I3 in peripherally spaced relationship. The teeth extend oppositely, overlapping or interdigitating when peripherally considered around the coil 3. Thus the toroidal flux field which is generated by the coil 3 completes the circuit through the members 5, I and H, thence into the inductor I, then escaping adjacently from the inductor into the adjacent pole teeth 3 l3 and completing the circuit through the ring 9 and back to the member or the sequence of the magnetic circuit may be reversed. The mean path of this flux field is indicated in cross section by dotted lines F in Fig. 1. This path is S -shaped through each pole.

Each of one set of claw teeth, such as for example l3, assume one polarity (north, for example; Fig. 5) and each of the other set of poles H assume the opposite polarity (south, for example). The poles act as field distorters and flux concentrators so that as the flux field sweeps the inductor l, due to relative motion, currents (eddy currents in the present case) are set up in the inductor whereby a magnetic reactive driving torque results.

As above stated and as shown in Fig. 1, the mean flux path in each pole is of S-shape extending from X through the heel part of the pole to a midpoint Y on the face 23 of the pole. The physical reason for this S-shape is the claw or L-shape of the pole in which the flux is carried. The, pole is so formed, as detailed in the aforesaid copending application, that each successive area which is substantially normal to said S-shape X, ,Y,'carries substantially the same flux density (and evenly distributed) as the area of the pole face 23, and this is true after leakage flux ahead of a given area has been accounted for.

As illustrated, each pole has a substantially rectangular quadrilateral pole face 23, except that there is a slight taper from the heel end 21 to the toeend IS. The pole faces lie virtually in a cylindric form surrounding and closely adjacent the outer cylindric surface of the inductor I. The heel line 2! of the poles are positioned to track the toe lines i9 of the adjacent poles. Each pole has a substantially flat triangular bottom 25, the plane of which extends at right angles to the plane of the respective supporting rings 1 or 9. This triangle is substantially right-angular. Its right-angular apex is designated 21. The outer end of each pole is formed as a flat radial face 63 flaring toward the inductor, the outer end of which is the line I9. The face or surface 63 narrows down to an apex at 65. A bevel line W connects the apex 21 and the apex 65. At is .shown a non-radial or bevel surface extending from heel line 2| to the outer surface of the ring I or 9. Each surface 35 flares in from the pole faces toward its respective ring 1 or 9. Each pole as a whole is joined to the ring 1 or 9 at a valley angle of approximately 45, as shown at 31.. The base of each triangle 25, where it merges with its respective ring, is substantially wider than the width of the pole face. The axial distance from the base to the apex 21 is less than the axial distance from the base to the end of the pole. The sides of each pole are symmetric geometric surfaces determined by pairs of generating side lines designated Q, R, S, T, U and V. The outermost side lines Q flare radially from one side of the. coil 3 toward the inductor. Both of these flares are reduced as successive pairs of lines are considered from the pole toward the central plane of the coil (note the angular progression of line pairs QS). The flares finally reverse so that they become tapers toward the faces of the pole and reverse radial flares; note line pairs TV. The line generators for the sides of the poles are adjusted in flare both radially and axially in such manner that successive cross sectional areas through the pole taken substantially normal to the mean flux path through the pole increase from the generally rectangular pole face toward the respective ring by amounts adapted to provide a substantially constant density of magnetic flux through each section and through the pole face. The specific dimensional criteria for the poles will be found in the aforesaid copending application. The mean cross section of magnetic material carrying the S-shaped flux field is increased from the pole face 23 to its root 31. The increase is such that after lost leakage of fiux between poles has been accounted for up to a given cross-sectional area normal to the mean flux path, the remainder of the flux left in the respective area .aas about the same density (number of lines per square inch) as the density in any other such cross-sectional area. Furthermore, this density is substantially evenly distributed over any such area. Thev ultimate result is that the flux field remaining for emanation from pole face 23 is equally distributed over the area of the face and may be pushed to saturation if need be throughout the pole face, depending upon the excitatio of coil 3. i

At numerals I5 are shown copper end rings brazed at their inside edges to the magnetic iron ring 2. Rings i5 are narrow relative to the width of the ring I. The ring I is of such width that the brazing connections l? of the copper end rings at their inside faces to the ring I lie slightly within the tracking planes of the ends of the heel and toe lines 2| and [9 of the poles. Connections [1 provide low-resistance inside edge contacts for the end rings. Thus, the ends of the claw-type poles project slightly beyond the inside edges of the end rings, as indicated at E. The extent of the projection is preferably of the order of one-sixteenth inch. The heel lines 2| of the poles track the toe lines 19 of the adjacent poles. It will be seen that the heel lines and toe lines of the poles on one side of the field member lie in a plane which intersects the respective end ring and which is spaced outward from the joint between the end ring and the inductor drum said preferred distance of one-sixteenth inch.

I have found that with the above-described construction, despite the fact that the ends of the poles project beyond the joint between the copper end rings and the inductor drum so that the flux emanating from the ends of the pole faces enters the non-magnetic copper, rather than magnetic iron, the torque capacity of the coupling is increased over and above what it would be if the ends of the pole faces were flush with the joints between the ends rings and the inductor drum, rather than being reduced as would be ordinarily expected. In the case of a coupling having clawtype poles shaped to provide constant flux density as herein disclosed and also as disclosed in the aforesaid copending application, there is a substantial increase in the torque capacity over the torque capacity of the same coupling constructed with the ends of the pole faces substantially flush with the joints between the copper end rings and the inductor drum.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A dynamoelectric machine comprising coax ial and relatively rotatable field and inductor members, one surrounding the other, said field member. comprising ansannular magnetizing element, magnetic rings on opposite sides of the magnetizing element, each ring having an annular seriesof claw-type poles extending axially across the magnetizing element between the latter and theinductor, the poles extending from one ring being interdigitated with respect to and annularly spaced from the poles extending from the other ring, each ring having notches between its poles receiving the ends of the poles of the other ring, each pole having a pole face opposed to the inductor with the pole faces of all the poles lying virtually in a cylindric form, and a generally triangular face opposite its pole face opposed to the magnetizing element convergin away from the respective ring with the triangular faces of all the poles lying virtually in a cylindric form, the base of each triangular face where it merges with its respective ring being substantially wider than the width of the pole face and the axial distance from said base to the apex of the triangular face opposite said base being less than the axial distance from the base to the end of the pole, the sides of each pole being formed as flaring surfaces convergent toward the pole face in the inner portion of the pole adjacent its junction with the ring and convergent away from the pole face in the outer end portion of the pole, said inductor member being provided with low-resistance end rings attached to the inductor in such positions that the ends of the pole faces project slightly beyond the inside edges of the end rings.

2. A dynamoelectric machine comprising coaxial and relatively rotatable field and inductor members, one surrounding the other, said field member comprising an annular magnetizing element, magnetic rings on opposite sides of the magnetizing element, each ring having an annular series of claw-type poles extending axially across the magnetizing element between the latter and the inductor, the poles extending from one ring being interdigitated with respect to and annularly spaced from the poles extending from the other ring, each ring having notches between its poles receiving the ends of the poles of the other ring, each pole having a pole face opposed to the inductor with the pole faces of all the poles lying virtually in a cylindric form, and a generally triangular face opposite its pole face opposed to the magnetizing element converging away from the respective ring with the triangular faces of all the poles lying virtually in a cylindric form, the base of each triangular face where it merges with its respective ring being substantially wider than the width of the pole face and the axial distance from said base to the apex of the triangular face opposite said base being less than the axial distance from the base to the end of the pole, the sides of each pole being formed as flaring surfaces convergent toward the pole face in the inner portion of the pole adjacent its junction with the ring and convergent away from the pole face in the outer end portion of the pole, said inductor member being provided with a pair of lowresistance end rings attached to the inductor in such positions that the ends of the pole faces project beyond the inside edges of the end rings a distance of the order of one-sixteenth of an inch.

3. A dynamoelectric machine comprising coaxial and relatively rotatable field and inductor members, one surrounding the other, said field member comprising an annular magnetizing ele ment, magnetic rings on opposite sides of the magnetizing element, each ring having an annular series of claw-type poles extending axially across the magnetizing element between the latter and the inductor, the poles extending from one ring being interdigitated with respect to and an-' nularly spaced from the poles extending from-the other'ringgeach'ring having notches between its poles receiving the ends of the poles of the other ring, each pole having a pole face opposed to the inductor with the pole faces of all the poles lying virtually in a cylindric form, and a generally triangular face opposite its pole face opposed to the magnetizing element converging away from the respective ring with the triangular faces of all the poles lying virtually in a cylindric form, the base of each triangular face where it merges with its respective ring being substantially wider than the width of the pole face and the axial distance from said base to the apex of the triangular face opposite said base being less than the axial distance from the base to the end of the pole, the sides of each pole being formed as flaring surface convergent toward the pole face in the inner portion of the pole adjacent its junction with the ring and convergent away from the pole face in the outer end portion of the pole, said inductor member being provided with a pair of axially spaced low-resistance end rings of narrow width in relation to the width of the inductor member, said end rings being so spaced and so positioned that the ends of the pole faces on one side of the field member lie in a plane normal to the axis of the field member which intersects the respective end ring outward of the inside edge of the end ring.

4. A dynamoelectric machine comprising coaxial and relatively rotatable field and inductor members, one surrounding the other, said field member comprising an annular magnetizing element, magnetic rings on opposite sides of the magnetizing element, each ring having an annular series of claw-type poles extending axially across the magnetizing element between the latter and the inductor, the poles extending from one ring being interdigitated with respect to and annularly spaced from the poles extending from the other ring, each ring having notches between its poles receiving the ends of the poles of the other ring, each pole having a pole face opposed to the inductor with the pole faces of all the poles lying virtually in a cylindric form, and a generally triangular face opposite its pole face opposed to the magnetizing element converging away from the respective ring with the triangular faces of all the poles lying virtually in a cylindric form, the base of each triangular face where it merges with its respective ring being substantially wider than the width of the pole face and the axial distance from said base to the apex of the triangular face opposite said base being less than the axial distance from the base to the end of the pole, the sides of each pole being formed as flaring surfaces convergent toward the pole face in the inner portion of the pole adjacent its junction with the ring and convergent away from the pole face in the outer end portion of the pole, the heel and toe lines of the pole faces of the poles at the respective sides of the field member lying in axially spaced planes normal to the axis of the field member, said inductor member being composed of a homogeneous magnetic material and having a substantially uninterrupted cylindric surface closely adjacent th pole faces, and being 2,624,153 7 8 provided with a pair of axially spaced low-re- REFERENCES CITED sistance end rings of narrow width in relation to the width of the inductor member, said end rings facing the field member and being so spaced and The following references are of record in the file of this patent:

positioned that said planes intersect the respec- 5 UNITED STATES PATENTS tive end rings outward of the inside edges of the Number Name Date end rings by a distance of the order of one-Six- 2,4'70,596 Winther May 17, 1949 teenth of an inch. 2,484,138 Winther Oct. 11, 1949 ANTHONY WINTHER. 

